Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"Gain media"”.
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Efficient THz lasers and broadband amplifiers based on quantum cascade gain media
One of the most important applications for Terahertz (THz) quantum cascade (QC) lasers is to provide compact and powerful frequency-stabilized solid-state sources as local oscillators in heterodyne receivers for astronomical studies. The first part of the thesis is dedicated to the device cavity …
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Novel II-IV semiconductor nanocrystal gain media : from amplified spontaneous emission to lasing
… (CdSe) nanocrystallites (NCs) as a novel lasing media. We begin with the synthesis of polymer/NC composites, in which the NCs are stabilized within a long-chain methacrylate polymer. This chapter serves to highlight the processing flexibility afforded by the NCs as well as some of the salient …
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Towards room-temperature Terahertz Quantum Cascade Lasers : directions and design
… to be limited by a fundamental trade-off between gain oscillator strength ful and upper-level lifetime [Tau]. This so-called "ful[Tau] tradeoff" is shown to explain the failure of designs which target [Tau] alone. A solution is proposed in the form of highly diagonal (low ful) active region design …
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Photoexcitation of rare earth and metal-halide molecules in the ultraviolet
In the search for new sources of light and gain media for lasers, lanthanide fluoride powders and rare earth tri-iodide salts in vapor phase have been studied spectroscopically by photopumping in the ultraviolet. Knowing the spectral response of these molecules with respect to incident light and …
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Theoretical design of photonic crystal devices for integrated optical circuits
… in two-dimensional photonic crystal slabs with gain media, where lasing occurs at saddle points in the band structure, in contrast to one-dimensional photonic crystals. We also design a photonic crystal slab with organic gain media that has a TE-like pseudogap. We demonstrate that such a slab …
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Towards terahertz dual-comb spectroscopy based on quantum cascade lasers
… several broadband homogeneous and heterogeneous gain media are characterized, and corresponding dispersion compensators are designed. All THz QCL frequency combs are fabricated in Microsystems Technology Laboratories at MIT using our group's standard process. By utilizing the broad spectral …
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Thermal Management, Beam Control,and Packaging Designs For High Power
… a diode laser array to uniformly pump rod shape gain media are also investigated.
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Low-cost, highly efficient, and tunable ultrafast laser technology based on directly diode-pumped Cr:Colquiriites
… technology based on diode-pumped Cr:Colquiriite gain media (Cr:LiCAF, Cr3+:LiSAF and Cr:LiSGaF). By using inexpensive single-mode diodes ($150) as the pump source, we have obtained continuous-wave (cw) output powers >250-mW with slope efficiencies >50%. Record cw tuning ranges were demonstrated …
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Loss compensation in a plasmonic nanoparticle array
… currently under exploration is the addition of a gain material in close proximity to the metallic nanostructures for loss compensation. Here the physics of light transport in a nanoparticle array, and the operation of gain media in contact with the structure, are described and analytically …
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A hybrid approach towards on-chip visible lasers
… crystal cavities that incorporate organic gain media resulting in an ultracompact low-threshold organic laser. We combined colloidal quantum dots with polymethylmethacrylate (PMMA) to create suspended polymeric cavities that showed enhanced spontaneous emission from the quantum dots. By …
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On the performance characteristics of multiple pass hydrogen fluoride chemical laser master oscillator/power amplifiers
… of input power, the number of passes through the gain media, location of the optical axis of the input beam and oscillator/amplifier flow field match/mismatch. The amplification ratio is an inverse function of the input power (intensity) and, for maximum amplification, the peak of the intensity …
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Effect Of Germanium Doping On Erbium Sensitization In The Erbium Doped Silicon Rich Silica Material System
… current literature this is attributed to exciton mediated excitation of the Er3+. By contrast, in these studies indirect excitation was observed for samples annealed at temperatures well below the onset of nanocrystal nucleation and growth (between 500ºC and 1000ºC), suggesting excitation via …
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Studies of Passive and Active Plasmonic Core-Shell Nanoparticles and their Applications
… CNP designs, including ones based on quantum dot gain media and study their performance characteristics with particular attention to the effect of the location of the gain material on the performance of these designs. We investigate the ability to control the scattered field directivity of the …
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Gewinngeschaltete Ti:Saphir-Laser mit ultrabreitem Abstimmbereich
Ti:Sapphire is one of the most preferred gain media for tunable solid-state lasers in the near infrared spectral region. Since the beginning of the new millennium the performance of tunable Ti:Sapphire lasers has gained a significant technology push by the steady increase of output power of …
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Ultrashort, High Power, And Ultralow Noise Mode-locked Optical Pulse Generation Using Quantum-dot Semiconductor Lasers
… of magnitude reduction of the linewidth in QD gain media. Ultralow phase noise performance (integrated timing jitter of a few fs at a 10 GHz repetition rate) was demonstrated from an actively mode-locked unidirectional ring laser. These results show that quantum dot mode-locked lasers are …
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Nonlinear optical frequency conversion of mode-locked all-solid-state lasers
… and λ= 700nm, since currently no other laser gain media exists that covers this region of the electromagnetic spectrum. This novel source is intended for application to multiphoton imaging. The first demonstration of additive pulse mode-locking of a diode-pumped Nd³⁺: YVO₄ laser operating in …
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Numerical Simulation and Experimental Investigation of Quantum Dash Lasers at Elevated Temperatures: Design and Operation of Monolithic InAs/InP Quantum Dash Ridge Laser Diodes Operating in the C-Band
… quantum dash laser. Quantum dash and dot gain media both exhibit spontaneous mode-locking, reduced sensitivity of their performance to temperature, and lower threshold current densities. Dashes additionally offer higher peak gain and broader gain bandwidths, but show higher phase noise …
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High Gain / Broadband Oxide Glasses For Next Generation Raman Amplifiers
… range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of the Raman active medium. In this context, glasses are the material of choice for this application due to their relatively broad …
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Organic lasers and nanostructred organic films for hybrid integration
… properties for colour conversion and as laser gain material are under investigation. To keep the LEPs' benefit of simple and low-cost fabrication, integration onto inorganic semiconductor devices such as in particular gallium nitride light emitting diodes (LEDs) is an important research topic. …
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